1. Field of the Invention
This invention relates to and has among its objects the provision of novel methods and apparatus for fermenting liquids. It is a particular object of the present invention to provide means for rapidly fermenting liquids on a continuous flow basis. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.
2. Description of the Prior Art
Fermentation processes are used extensively in the production of beverage products such as beer, wine, whiskey, brandy, and the like. Continuous fermentation of liquids is desirable because of its economic and practical advantages. Batchwise processing results in a considerable amount of settling of the fermentation culture particularly during the latter stages of non-agitated fermentation. In continuous fermentation levitation of the fermentation culture by substrate flow is an important advantage.
Three basic types of continuous flow fermentors are described in Biotechnology and Bioengineering, Vol. XVI, pp. 1611-1631 (1974), by Wick et al. The type of fermentor is determined by the direction of substrate flow: upward flow, slant flow, and horizontal flow. Upward flow is generally obtained in an open cylinder or in a filter fermentor. Slant flow tube and slant flow spiral tube fermentors provide slant flow. Horizontal flow usually results when shallow pans are employed in the fermentation process.
The above described methods have certain inherent disadvantages which render them difficult to use in large scale fermentations. With the upward flow and slant flow methods the tube can be lengthened to accommodate more liquid. However, long tubes become impractical to work with and difficult to conform to the confines of a processing plant. Increasing the diameter of upward flow or slant flow tubes is also disadvantageous for the same reason that horizontal flow is undesirable, namely, settling of the fermentation culture.